最大乘积

Posted 2021-02-14 bernieloveslife

给定一个无序数组，包含正数、负数和0，要求从中找出3个数的乘积，使得乘积最大，要求时间复杂度：O(n)，空间复杂度：O(1)

def solve():
    n = input()
    a = input().split()
    for i in range(len(a)):
        a[i] = int(a[i])
    m1,m2,p1,p2,p3 = 0,0,0,0,0
    for i in a:
        if i<0:
            if i<m1:
                m2 = m1
                m1 = i
            elif i<m2:
                m2 = i
        elif i==0:
            zero = True
        else:
            if i>p3:
                p1 = p2
                p2 = p3
                p3 = i
            elif i>p2:
                p1 = p2
                p2 = i
            elif i>p1:
                p1 = i
    if p2==0 or p1==0:
        return m1*m2*p3
    # print(m1,m2,p1,p2,p3)
    return max(p1*p2*p3,m1*m2*p3)
 
print(solve())